1. Field of the Invention
The present invention relates to an Auditory Pathway Stimulator for management through central habituation of patients suffering from Tinnitus or Hyperacusis, or both. More particularly, the present invention relates to a system and method for reducing the debilitating effects of tinnitus by means of an all-in-the-canal, open-ear, noise stimulus of the auditory pathway.
2. General Background of the Invention
Tinnitus is a wide spread auditory symptom affecting approximately 17% of the general population growing to 33% in the elderly. This percentage translates to about 44 million people in the United States. Most who experience tinnitus manage well, in that it is not disruptive in daily life. However, approximately 25% of people experiencing tinnitus are encumbered to the extent that they actively seek help. The above statistics correspond to approximately 10 million sufferers in the United States and 2 million of these sufferers are debilitated by tinnitus to the point of total disruption of the quality of life (Jastreboff P. J., Gray W. C., and Gold S. L.: "Neurophysiological Approach to Tinnitus Patients", The American Journal of Otology, 17:236-340 .COPYRGT.1996). In fact, some extreme cases have led to suicide. At present, there is no cure for tinnitus. Most sufferers are told by medical and audiological professionals they should "learn to live with it."
Over 300 research projects funded by public and private agencies have been conducted to address tinnitus and its harmful effects during the last two decades. A cure is still unforeseen in the near future. This invention is an important step to a systematic solution with long-term significant results.
The concept of tinnitus is difficult to convey since it is a "Phantom Auditory Perception" representing lack of certain neuro activity in the auditory system rather than an increased activity. It is also a symptom associated with many auditory and non auditory pathologies.
Unmanageable tinnitus is due to a conditioned reflex between the central auditory pathways and the limbic system. In short, when the auditory brainstem detects a new sound such as tinnitus it automatically assigns high priority to the new auditory signal. This detection in turn provokes a negative emotional association in the limbic system producing a very strong conditioned reflex perceived as a thread which activates the body's fight-or-flight response and since this is an internally generated sound one can not control its volume or remove themselves from it.
In the case of tinnitus, once the new pattern of auditory neural activity is detected and locked into the limbic system the tinnitus becomes extremely prominent. Basic neuroscience predicts that it is relatively easy to reverse this signal recognition process by exposing the patient to low levels of broad band noise for a long period of time. This broad band noise will interfere with the tinnitus recognition process making it more difficult to separate the tinnitus signal from background neuronal activities and, since there are no longer other processes increasing recognition of this intruding signal the tinnitus becomes no longer detected.
In recent years masking of tinnitus using various noise signals of adjustable width and amplitude have been developed as a result of scientific research done by Jack Vernon. These devices yielded very limited success. More recently, a neurophysiological model of tinnitus management has been developed by Pawel Jastreboff. Using specific protocol, attempts were made to habituate patients to the presence of tinnitus. Habituation infers training patients not to be aware of tinnitus except when deliberately focusing their attention on it. Even then, perceived tinnitus should no longer induce annoyance or irritation.
It has been shown that the introduction of a noise signal can help in the therapy. Behind-the-ear noise generators have yielded an 83 percent success rate. Yet the units remain big, cumbersome and cosmetically unappealing.
Manufacturers of hearing aids are regulated by the United States Food and Drug Administration (FDA) as a medical device establishment. Hearing aid components used in the assembly of custom open-ear tinnitus habituators and produced as a combined hearing aid/tinnitus habituator device or as a stand-alone tinnitus device will be categorized, not as a Class I hearing device, but rather as a Class III prosthetic device under 21 C.F.R. .sctn. 874.3400 entitled "Tinnitus masker". The tinnitus habituator differs from the tinnitus masker in that it does not emit a signal intended to overpower the tinnitus head/ear noise, but to stimulate the auditory pathways with a broad-band low-level signal. Its intent, however, is to aid in tinnitus and FDA has decided the device described in this application will fall into the Class III classification. FDA regulates medical devices based on safety and effectiveness. The hearing aid components used in the construction of the tinnitus habituator have been used in the assembly of millions of Class I hearing aids and are therefore known to be safe when used as directed. The efficacy is the issue, in that there is no established protocol by FDA in the management of tinnitus. The Class III classification stems from the absence of this protocol. The Class I level would be more cost-efficient to produce and in turn reduce the cost to the public. It is the protocol that teaches the patient to focus on the signal of the tinnitus habituator and not focus on the tinnitus head noise which enables the tinnitus device though central auditory habituation to reduce the debilitating effects of tinnitus or hyperacusis. Tinnitus habituators without a well designed therapy would not be significantly effective. Also, masking tinnitus via a traditional masker is counter productive (Gold S. L., Gray W. C., Hu S., and Jastreboff P. W. "Selection and Fitting of Noise Generators and Hearing Aids for Tinnitus Patients", Proceedings of the Fifth International Tinnitus Seminar 1995 edited by Reich G. E. and Vernon J. A. .COPYRGT.American Tinnitus Association, Portland Oreg. U.S.A. 1996 p.312-314; Jastreboff P. J. and Hazel J. W. P. "A Neurophysiological Approach to Tinnitus: Clinical Implications" British Journal of Audiology, 1993. 27. 7-17). It is very important to avoid masking tinnitus. In fact, there are reports of patients having long term "masking" therapy who realized no relief from the perception of the tinnitus or the annoyance resulting from the tinnitus. After entering into habituation therapy, both the perception of and the annoyance from tinnitus were reduced (Jastreboff P. J., Gray W. C., and Gold S. L.: "Neurophysiological Approach to Tinnitus Patients", The American Journal of Otology, 17:236-340 .COPYRGT.1996).
Products designed to be used to fill the room with a low level noise, not FDA regulated, have proven to offer minimum effectiveness, because sound reaching the ear drum is unstable and inconsistent due to head shadow effect, occlusion to the external ear canal, and the Doppler effect caused by motion of the patient's head, such as turning back and forth vigorously. Additionally, the size of this unit makes it difficult to transport and impractical to use outside of the home since the noise would distract others.
U.S. Pat. No. 5,403,262 issued to Gooch describes a circuit means of random noise generation, which is digitally processed to selected center frequencies, bandwidth and intensity. A random noise signal is transduced to acoustical energy by a speaker or headphone. Other means of delivering the masking signal to the patient's ear may be by way of using a low-power transmitter or electromagnetic coil to deliver the signal from the tinnitus masker to a receiver worn in or on the sufferer's ear. Gooch's circuit is intended for room noise generation to mask tinnitus, not habituate it, as a patient goes to sleep.
U.S. Pat. No. 5,325,872, issued to Westerham et al., discloses an invention which relates to a Tinnitus masker with one or more signal generators, a controllable amplifier, transducers and comprises means for generating a continuously repeated, sinusoidal pure-tone signal which continuously and slowly moves through an audiofrequency range in a cyclic manner to remove tinnitus for a period of time. Westerham et al. predicates its design of the masker on the reasoning that "tinnitus is very frequently perceived as a tone". The described embodiment is a behind-the-ear (B-T-E) device.
U.S. Pat. No. 4,222,393 issued to Hocks et al. describes a Tinnitus masker device whereby the patient is subjected to external sounds of different pitch, one right after another, to enable the patient to identify the particular external sound having the same pitch as the subjective tinnitus sound perceived by the patient. The patient is then provided a power-operated sound generator producing a range of frequencies extending above and below the perceived pitch to mask the tinnitus sound. The tinnitus masker may be worn in the same manner as a hearing aid or combined with one. Once again, the device is a masker intended to immerse the tinnitus head noise below audibility. This is accomplished by using a noise signal with a patient-selected center frequency where the output noise signal is of broader band-width and intensity than the tinnitus therefore facilitating a masking effect of the tinnitus. The actual noise generation of the masker is by a noise generator. It can only be produced in a behind-the-ear instrument.
U.S. Pat. No. 5,167,236 issued to Junker describes a behind-the-ear Tinnitus-masker which is an electronic circuit designed so that the sound spectrum produced through an ear-piece contains a line spectrum with a fundamental tone.
U.S. Pat. No. 4,870,688 issued to Voroba et al. describes a hearing aid comprising an electronic circuit designed using a pseudorandom frequency noise generator as a sound source to be connected to a hearing aid circuit for use in patients with "ringing" or "buzzing" in the head, commonly called tinnitus. The drawings in the patent do not define the object and only identify a standard hearing aid microphone as the source.
Other patents that may be of interest include the following:
U.S. Pat. No. 5,024,612, External ear canal pressure regulating device and tinnitus suppression device; PA1 U.S. Pat. No. 5,628,330, Apparatus for treating people afflicted with tinnitus; PA1 U.S. Pat. No. 4,735,968, Method of treating tinnitus with AOAA; PA1 U.S. Pat. No. 5,279,292, Charging system for implantable hearing aids and tinnitus maskers; PA1 U.S. Pat. No. 5,064,858, Protected complex of procaine for the treatment of symptoms from narcotics addiction, tinnitus and Alzheimer's disease; PA1 U.S. Pat. No. 4,954,486, Furosemide as tinnitus suppressant; PA1 U.S. Pat. No. 4,984,579, Apparatus for treatment of sensorineural hearing loss, vertigo, tinnitus and aural fullness; PA1 U.S. Pat. No. 4,956,391, Protected complex of procaine for the treatment of symptoms from narcotics addiction, tinnitus and Alzheimer's disease; PA1 U.S. Pat. No. 5,589,183, Method and apparatus for treatment of neurogenic diabetes mellitus, and other conditions; PA1 U.S. Pat. No. 4,759,070, Patient controlled master hearing aid; PA1 U.S. Pat. No. 4,226,248, Phonocephalographic device; PA1 U.S. Pat. No. 5,563,140, Use of 1-(aminoalkyl)-3-(benzyl)-quinoxaline-2-one derivatives for the preparation of neuroprotective compositions; PA1 U.S. Pat. No. 4,680,798, Audio signal processing circuit for use in a hearing aid and method for operating same; PA1 U.S. Pat. No. 3,764,748, Implanted hearing aids;
Whether the failure of current tinnitus devices is due to the incomplete or inaccurate clinical knowledge or whether the failure is existing product performance, the end result is tinnitus and hyperacusis patients are experiencing an inadequate quality of life.
All patents mentioned herein are incorporated herein by reference.